1. Field of the Invention
This invention relates to a punch press for piercing a ceramics type green sheet, more particularly to an improvement of a punching press machine for piercing various forms and sized perforations passing through upon its surface of the green sheet before sintering process in the art of utilizing it for IC substrates and the like.
2. Description of the Prior Art
Conventionally, it is known that a green sheet is formed as a thin sheet by the so-called Doctor blade method or Calendar method, which is made from a mixture of compounds including pulverized ceramics, an organic bonding agent, a plasticizer, a solvent and the like. The raw sheet before sintering has a rich plasticity, flexibility and workability. Therefore, it is known that it can be easily cut-off, drilled, punched, bonded and the like, thus useful for IC substrate and the like pursuant to a sintering process in the art.
As a process conception for making a green sheet, for example, initially a raw material of ceramic compound is coated on a tape (such as a polyester resin film and the like) uniformly with a predetermined thickness, and then dried in ordinary course. Secondly, the ceramic sheet layer is peeled off from the tape for obtaining a green sheet slip shown as a green color namely, wherein it is passed to a piercing process by using an exclusive type punch press machine.
In the above conventional means of piercing the green sheet, however, it has such a disadvantage that since the thickness of the green sheet which has been peeled off from the tape is too thin approximately 0.1 mm), the handling of the green sheet is so troublesome as its workability in the spot, consequently there is no way to improve the productivity and the perforation work is seriously difficult.